Remote control transmitting device



S t, 19, 1961 J. s. NABER ET AL 3,001,066

REMOTE CONTROL TRANSMITTING DEVICE Filed May 22, 1958 [Ill Gm; NierJzza/z J3arme as fer flitys.

3,001,066 REMOTE CGNTROL TRANSMIG DEVICE Joseph S. Naber, Wheeling, and Arthur H. Maciszewski, River Forest, 111., assignors to ARE. Products, Inc, River Forest, Ill, a corporation of Illinois Filed May 22, 1958, Ser. No. 737,069 3 Claims. (Cl. 25017) This invention relates to transmitting devices for remotely actuating apparatus, and is particularly related to transmitting devices which are adapted to be disposed within vehicles for remotely actuating mechanical devices such as garage door operators.

Various devices have been employed for remotely opening and closing a garage door from a vehicle. Most of these devices employ a garage door operator for opening and closing the door, a receiving device connected to the operator for actuating it, and a transmitting device usually located in the vehicle. At present, the most prevalent systems being used for controlling garage doors use radiation type remote control devices, or induction type remote control devices. In the radiation type device, a radio frequency signal is generated and impressed upon an antenna, or radiator, for transmission, and the radiated signal is detected by a receiver. Such devices are in essence radio transmitters and must comply with the Federal Communications Commission regulations. An induction type remote control device generates an induction field which is directly detected by a receiving device at a location remote from the induction generating device.

In both the radiation type and the induction type of garage door remote control systems, the induction or radiation field requires considerable energy, and vacuum tube oscillators have been employed to generate these fields with adequate energy. As a result, the transmitting devices require substantial potentials, and in the use of these devices in vehicles, a power source is required to transform the available direct current power in the vehicle to suitable potentials for operating the transmitting device.

As a result of this fact, the cost of the transmitting device for both radiation and induction type remote control systems is relatively high. It is one of the objects of the present invention to provide a transmitting device for a remote control system which may be directly powered from a relatively low voltage direct current battery.

It is, of course, well known that radio-frequency signals may be generated without the use of vacuum tubes by means of spark gap oscillators. In the conventional spark gap oscillator, a spark gap, condenser, and coil are connected in series, and a power source is connected in parallel with the condenser through a relatively high resistance. When the charge upon the condenser builds up to a sufficient value, the spark gap breaks down and a damped wave train is produced in the series circuit. Since spark gap oscillators require suificiently high potentials to break down the spark gap, they require some means to transform the low voltage direct current from the battery of a vehicle, or the like, to a suitable potential. One of the devices used for this purpose is a transformer provided with an interruptor in its primary circuit, the battery being connected in series with the interruptor and primary. The potential developed across the secondary of the transformer is then sufficient to cause a spark discharge acrossthe spark gap. It is one of the objects of the present invention to provide a transmitting device which directly excites a tank circuit from a relatively low direct current source without requiring the potential of the power source to be raised. In other words, it is an object of the present invention to provide a transmitting device which directly employs the energy Patented Sept. 19, 19%1 of a direct current battery, or other direct current power source, to shock excite a tank circuit, thus eliminating the cost and bulk of any means between the direct current power source and the tank circuit to transform the potential of the power source to a higher value.

In addition, it is an object of the present invention to provide a transmitting device using shock excitation of a tuned circuit in which a mechanical circuit breaker is employed, thus providing an inexpensive device.

These and other objects of the invention will be more readily understood, as well as preferred constructions of the invention and other advantages thereof, from a further reading of this disclosure, particularly when viewed in the light of the drawings, in which:

FIGURE 1 is 'a schematic electrical circuit diagram of a transmitting device constructed according to the teachings of the present invention;

FIGURE 2 is a graph illustrating the wave form of the electrical signal appearing in the tank circuit of the transmitting device shown in FIGURE 1;

FIGURE 3 is a schematic electrical circuit diagram of another transmitting device constructed according to the teachings of the present invention;

FIGURE 4 is a graph showing the wave form of the electrical signal in the tank circuit of the transmitting device illustrated in FIGURE 3; and

FIGURE 5 is a graph illustrating the wave form of the electrical signal appearing in the tank circuit of another transmitting device constructed according to the present invention.

In the transmitting device illustrated in FIGURE 1, a source of direct current voltage, such as the storage battery 10 of a vehicle, is connected in a series circuit with an interruptor 12, a circuit breaker in the form of a buzzer 14, and a tank circuit 16. The tank circuit 16 has a coil 18 and a condenser 20 connected in parallel, and is adapted to resonate at a fixed frequency. The interruptor 12 has a pair of contacts 22 and 24 contact 24 being mounted by a resilient arm 25 and contact 22 being secured to a resilient arm 27 which has a weight 29 at its end and is adapted to vibrate at a fixed frequency. The interruptor 12 may be of the type disclosed in the patent application of Arthur H. Maciszewski and Richard Goldstein, entitled Keying and Coding Device, Serial No. 409,109, now Patent No. 2,844,683, and is used to provide coding pulses in the signal produced by the transmitting device which may then be employed to key a receiving device to the particular transmitting device. In this manner, a receiving device may be keyed to a particular transmitting device and used to actuate a given door operator, so that a given transmitting device will open and close only the garagedoor associated with the particular receiving device.

The buzzer 14 also interrupts the fiow of current through the tank circuit 16. It has an iron cored coil 26 which has one end electrically connected to the interruptor 12 and the other end connected to a magnetic armature 28. A stationary contact 30 is disposed adjacent to the armature 28 and is normally in contact with armature 28. The contact 30 is directly connected to the tank circuit 16. A switch 32 is also connected in series with the battery 10 and tank circuit 16.

When the switch 32 is closed and the interruptor 12 operating, the buzzer 14 will be actuated during periods of contact of the interruptor 12. The inventors have found that the interruptor 12 should have a frequency between 5 and 60 cycles per second, and in a preferred construction of the transmitting device, the interruptor 12 has a frequency of approximately 20 cycles per second. The contacts 22 and 24 remain closed for a period of approximately 50 percent of the cycle. During the period of conduction of the interruptor 12, the buzzer 14 oper-' ates, thereby making and breaking contact between the contact 30 and armature 28, and opening and closing the series circuit. The frequency of the buzzer 14 should be as high as possible, at least 200 cycles per second, and in the preferred construction described, 1000 cycles per second. Further, the tank circuit 16 should have a resonant frequency between kilocycles per second and 3000 kilocycles per second, the preferred construction having a resonant frequency of approximately 300 kilocycles per second, in order to operate efficiently as an induction device. When the buzzer 14 is operating, a series of damped wave trains with the frequency of the tank circuit 16 occur in the tank circuit 16, the repetition rate of the damped waves being the frequency of the buzzer 14. The entire wave train, of course, is interrupted at the frequency of the interruptor 12. FIGURE 2 illustrates a portion of the wave train appearing in the tank circuit 16.

If the buzzer 14 were eliminated from the circuit, each opening of the contacts 22 and 24 of the interruptor 12 would produce a single damped Wave train in the tank circuit 16 of the transmitting device. This damped wave train would contain a relatively small amount of energy. The function of the buzzer I4 is to provide a series of damped wave trains during each period of the interruptor 12, rather than a single wave train, thus providing a relatively large amount of energy in the tank circuit 16.

It is believed to be preferable to use the inductive field of the tank circuit 16 to actuate a garage door operator, since this facilitates compliance with the Federal Cornmunications Commission regulations governing the transmission of radiated signals. The principal disadvantage arising from the use of the inductive field of a transmitting device is the limited range through which the inductive field can be used to couple the signal from the transmitting device to the receiving device. In addition, it is desirable to generate the maximum energy for a given power source in the tank circuit 16 of the transmitting device, and to employ the proper ampere turns ratio in the coil at the input of the receiving device. By the use of the buzzer 14, the inventors are able to increase the energy applied to the tank circuit 16 of the transmitting device, and thus satisfy one of the conditions for maximum permissible range of transmission by an inductive field.

The inventors have found that the buzzer 14 should have a frequency of at least 200 cycles. per second in order to pack sufficient energy into the tank circuit 16 to provide an induction field of sufficient strength to be satisfactory when using a 6 volt battery source, such as is generally employed in moving vehicles, and in the preferred construction described herein the frequency of the buzzer of 1000 cycles per second. The frequency of the buzzer has an upper limit set by the construction technique presently used; however, the present invention may be practiced with a buzzer having a frequency up to onetenth of that of the tank circuit.

While the transmitting device of FIGURE 1 is described as an induction type device, it may also be used as a radiation type device. To do so, a radiator 34 is coupled to the tank circuit 16 by a coil 36 which is connected to ground. In FIGURE 1, the radiator 34 and coil 36 are shown in dotted lines to indicate the construotion required for both modes of operation.

The embodiment of the invention illustrated in FIG- URE 3 is a modification of the transmitting device illustrated in FIGURE 1 containing a vacuum tube oscillator which is employed to generate higher radio-frequencies than readily obtainable with the device illustrated in FIG- URE l. The device of FIGURE 3 is particularly suitable for the transmission of radiated signals.

In this embodiment of the invention, a battery 40, or other low voltage direct current source, is connected in a series circuit with an interruptor 42, a buzzer 44, and an inductance 46. The interruptor 42 may be identical to the interruptor 12, illustrated in FIGURE 1, and the buzzer 44 may be identical with the buzzer 14, illustrated in FIGURE 1. The inductance 46 is a large inductance, and has a resonant frequency much below the desired frequency of operation, as will be explained hereinafter. A potential develops across the inductance 46 which may be used to power an oscillator 48, such as the conventional Hartley oscillator which is illustrated. The oscillator 48 could also be a tuned-plate tuned-grid, Colpits, Meissner, or other well known oscillator.

In the particular construction described, the oscillator 48 employs a vacutun tube 50 which has a plate 52 connected to the junction of the inductance 46 and buzzer 44. The plate 52 is also connected to one end of a tank circuit 54 through blocking condenser 56. The other end of the tank circuit 54 is connected to the grid 57 of the vacuum tube 50 through a condenser 58 and resistor 59 connected in parallel. The tank circuit 54 has a coil 60 and a condenser 61 connected in parallel, and the coil 60 is provided with a tap 62 which is connected to the oathode 64 of vacuum tube 50. The position of the tap 62 determines the amount of feed back between the plate and grid circuits of the oscillator, as is conventional in Hartley oscillators.

The coil 46 has a sufficiently high inductance so that any resonant frequency it might have with its distributed capacitance is much lower than the frequency of the buzzer 44, and as a result, each closing of the interruptor 42 results in the formation of a single voltage pulse across the coil 46 for each cycle of the buzzer 44. The form of these pulses appearing across coil 46 is shown in FIG- URE 4 by the envelope 66. This pulse develops from the breaking of the circuit by the buzzer 44, and during this period when the interruptor 42 is closed and the buzzer 44 is open, a sufficient potential develops across the coil 46 to set the oscillator 48 into oscillation. As a result, the current flowing through the tank circuit 54 of the oscillator 48 takes the form of a sine wave having the frequency of resonance of the tank circuit 54, shown at 68 in FIGURE 4.

In a preferred construction of this embodiment of the invention, the interruptor 42 operates at a frequency of 20 cycles per second, the buzzer 44 operates at a frequency of 1000 cycles per second, and the tank circuit 54 resonates at a frequency of 900 megacycles per secand.

The wave form of the electrical signal generated in the tank circuit 54 of the oscillator 48 may be substantially modified if a condenser 70, shown in dotted lines in FIGURE 3, is connected in parallel with the coil 46 forming a resonant tank circuit 72 with a frequency of resonance very much higher than that of the buzzer 44. In a preferred construction of the invention, the resonant frequency of this tank circuit 72 is 150 kilocycles per second. Under these conditions, a damped wave train appears across the coil 46, the frequency of the wave train being the frequency of resonance of the tank circuit 72. Since the oscillator 48 will oscillate only during the positive portions of this damped wave train, the current flowing in the tank circuit 54 of the oscillator 48 takes the form illustrated in FIGURE 5, name- 1y, a plurality of groups of sine waves 76 having amplitudes which also vary half-sinusoidally, each successive group being of smaller amplitude.

The addition of the condenser 7 0 forming tank circuit 72 provides a second coding interval available to key the receiving device with the transmitting device for remote control operation. The frequency of the buzzer may also be employed for coding.

If the transmitting device illustrated in FIGURE 3 is to communicate with a receiving device by its induction field, no radiator is provided. However, if it is desired that contact with the receiving device be maintained by radiation, a coil 78 is coupled to the coil 60' of the tank circuit 54, and a radiator 80 is connected to the coil 78. The coil 78 and radiator 80 are indicated in dotted lines in FIGURE 3, since these elements are not essential to the operation of the transmitting device.

When the condenser 70 is used, it is possible to eliminate the buzzer 44 from the circuit illustrated in FIG- URE 3 by providing the tank circuit 72 with a suificiently high Q and a resonant frequency very much smaller than the resonant frequency of the tank circuit 54. The inventors have found that the buzzer 44 is not necessary if the frequency of the tank circuit 72 is no greater than one-tenth that of the tank circuit 54 and has a Q of at least 50.

A receiver to operate in conjunction with the disclosed transmitting device has not been specifically illustrated in the present disclosure because a suitable receiver is disclosed in the patent of Julius J. Hupert and Richard I. Goldstein, No. 2,695,977, issued November 30, 1954, entitled Remote-Relay Control by Radio.

In the foregoing disclosure, the interrupter, or buzzers 14 and 44 are illustrated as electromechanical devices. It is, however, to be understood, that these interruptors may be purely mechanical.

From a reading of the foregoing disclosure, many modifications and improvements upon the present invention will be apparent to the man skilled in the art. It is therefore intended that the scope of the present invention be not limited by the foregoing disclosure, but rather only by the appended claims.

The invention claimed is:

1. A radio-frequency generator comprising, a direct current power source, a buzzer having a pair of circuit breaking contacts and a frequency of at least 200 cycles per second, a periodic interrupter having a pair of circuit breaking contacts and a frequency between 5 and 60 cycles per second, a tank circuit having a coil and con denser connected in parallel with a resonant frequency of approximately 300 kilocycles per second, the direct current power source, circuit breaking contacts of the buzzer, circuit breaking contacts of the periodic interrupter, and tank circuit being connected in a series circuit, and a vacuum tube oscillator having a frequency of approximately 900 megacycles having power input terminals connected across the coil.

2. A radio-frequency generator comprising, in combination, a power source including a buzzer having a pair of circuit breaking contacts and a mechanical frequency of resonance of at least 200 cycles per second, a periodic interrupter having a pair of circuit breaking contacts and a mechanical frequency of resonance between 5 and cycles per second, an inductance, a condenser connected in parallel with the inductance, a direct current source, the circuit breaking contacts of the buzzer, the circuit breaking contacts of the interrupter, the inductance and the direct current source being connected in a series circuit, and a vacuum tube oscillator having a frequency about ten kilocycles per second having a pair of input terminals, the inductance being connected across the input terminals of the oscillator.

3. A radio frequency generator comprising the elements of claim 2 wherein the condenser and inductance have a resonant frequency below the frequency of the buzzer.

References Cited in the file of this patent UNITED STATES PATENTS 1,760,479 Colman May 27, 1930 2,410,087 Litton Oct. 29, 1946 2,695,951 Hupert et al Nov. 30, 1954 2,844,683 Maciszewski et a1 July 22, 1958 

